1. Field of the Invention
The present invention relates to systems and methods of digital processing, and in particular to low-power logic circuits for performing mapping functions.
2. Description of the Related Art
A pulse-shaping digital filter is a digital system consisting of a data rate expander (that inserts zeros between successive input bits) followed by a digital filter operating at the higher data rate. The system accepts an input stream of symbols which, in the most elementary form, is a stream of one-bit data, and produces an output stream of B-bit data (where B is a fixed positive integer) having a waveform suitable for processing by a digital-to-analog converter (DAC). The DAC yields an analog signal whose waveform contains the original bit-stream's information while having its frequency content appropriately bandlimited for transmission through some given communication channel.
Pulse-shaping filters, both analog and digital, have been well studied in the literature for several decades and their importance in the implementation of practical communication systems has only increased as the interest in transmitting digital data has increased. The recent popular interest in wireless digital communication systems such as digital cellular telephones has highlighted the need for digital filter implementations that minimize power dissipation. Techniques have been proposed which permit reduced power consumption in digital processing circuits, however, there is a need for logic circuits that can implement the required logic without unnecessary power consumption. The present invention satisfies that need.